1. Field of the Invention
This invention is a structure for expanded metal that creates an aerodynamic leading edge. A method is also provided for making the structure. In one specific application, the expanded metal is used as a substrate material for a catalyst in an automotive converter.
2. Brief Description of the Related Art
Expanded metal is an extremely versatile material structure. It is used in numerous applications from fascia panels, balcony railings, lawn furniture, enclosures, walkways, to supports for catalysts in automotive catalytic converters.
Expanded metal comes in two basic configurations, standard and flattened. In the standard configuration, a plate of metal is cut at an angle of 90 degrees to the surface and then expanded, by pulling, to form an aperture having the ubiquitous diamond shape. The standard process leads to an expanded metal that has a rectangular strand. The flattened configuration is the standard configuration with the further processing step of cold rolling. In the flattened configuration, the aperture remains diamond shaped and the strand cross-section remains rectangular.
Another common processing technique is stretching. In stretching, the metal is pulled after expansion with the goal of rotating the strands. The strands, however, after rotation still have a rectangular cross-section.
In yet another expanded metal configuration, the cross-section of the expanded metal is hexagonal with two acute angles. In this configuration the acute angles of the strand are oriented in the plane of the aperture.
As indicated above, expanded metal has numerous applications. In one particular category of uses the aerodynamic design of strand is becoming critical. Expanded metal has been used for years in applications where a fluid flows through the diamond shapes. As expanded metal is used in applications where the velocity of the fluid flow is becoming greater and greater the pressure drop created by the profile of the strand is becoming increasingly problematic.
Various solutions have been developed to reduce the pressure drop created by the profile of the strand. These solutions have focused on orienting the strand into the flow, as discussed above, or mounting the expanded metal in the fluid flow at an angle to in effect orient the strand into the flow. While these approaches do improve pressure drop characteristics, a strand with an essentially rectangular cross-section is still used. It would be desirable if the strand itself had a more aerodynamic cross-section.